1. Field of the Invention
The present invention relates to an ink absorber used in ink jet recording apparatus for performing recording as ejecting ink, an ink tank and an ink jet cartridge using the ink absorber, a process for producing the ink tank, a fiber body used in the ink tank, and an ink jet recording apparatus capable of mounting the ink jet cartridge. More specifically, the invention concerns the field of ink jet recording as applying a fiber material to the ink absorber.
2. Related Background Art
It is conventionally general to provide the ink tank used in ink jet recording with a mechanism for adjusting the pressure of ink stored in the ink tank from the viewpoint of maintaining a good ink supply property to the ink jet recording head, and the like. Since this pressure is for making the pressure at an ejection outlet negative relative to the atmospheric pressure, it is called as a negative pressure.
One of the easiest methods for generating the negative pressure is a method for setting an ink absorber in the ink tank to utilize the capillarity of the absorber. Particularly, a foam such as urethane sponge or the like is used as an ink absorber from the standpoint that it is easy to fabricate a porous structure with uniform porosity excellent in capability of retaining the ink.
The foam of urethane sponge or the like needs a film removing process before use as an ink absorber, because in a state of the foam just after fabricated, foam cells each exist in an isolated state from each other by films. Some types of ink used had a possibility of appearance of an eluate because of chemical stability of the foam itself, which sometimes imposed a restriction on the ink used.
In order to solve the above problem, recently proposed are a method for making the ink absorber of a fiber bundle as described in Japanese Laid-open Patent Application No. 6-79882 and a method for making the ink absorber of a felt being a fiber material as described in Japanese Laid-open Patent Application No. 7-323566.
However, the many ink tanks using the conventional fiber bundle as described above include a small number of fibers linearly existing or a bundle of fibers packed in one direction, and thus have little capability of retaining the ink. Therefore, there is a possibility of contraction of fibers in a bundle form due to charge of ink.
On the other hand, the following technological subjects were found out as to the ink tanks using the felt as described above. Namely, when the conventional felt was used as an absorber, it was very difficult to make a single layer of a low-density felt capable of generating a desired negative pressure as an ink absorber with an increase of the size of ink tank.
It is thus usually necessary to use a laminate of felts. However, since a felt laminate is easy to deform, when blanked, in the blanking direction, advanced techniques are required to raise the blanking accuracy of felt. Since the strength of the felt laminate is lower in the laminate direction than in the directions perpendicular to the laminate direction, there is a possibility that the felt is broken when an ink supply tube is put into the laminate surface and air reserved in that portion could impede supply of ink. Thus there is a limitation on the position of the ink supply tube. There was a further possibility of runout in ink or the like at interfaces of the laminate.
Configurations of the recent ink tanks tend to become more and more complicated in order to effectively utilize the limited space in the ink jet recording apparatus. In addition, the tanks are often provided with a mechanism for preventing erroneous mounting with spread of multi-color arrangement of ink used, which accelerates the complexity tendency of configuration more. In manufacturing the ink absorbers used in the ink tanks of such complicated configurations, there was the problem that manufacturing steps became complex for blanking in predetermined shapes, as described above.
Namely, blanking is done in one direction for the felt laminate up to a predetermined thickness, and thus, the configurations of the ink absorbers obtained in this manner are limited to those as shown in FIGS. 14A and 14B.
For example, for obtaining the configuration shown in FIG. 14C, a process in the direction shown by arrow b is necessary in addition to a process in the direction shown by arrow a, but such processes are not carried out by blanking, but often by hand. Such hand works would raise problems of increasing the manufacturing cost, lacking in stability of configuration, and so on. These problems will arise not only in the cases using the felt, but also in the method using the foam. The problems are significant especially in the cases where the ink tank is shaped further including an inclination portion or recessed and projected portions. On the other hand, in the case of the method using the conventional fiber bundle as described above, it was also difficult to insert the fiber bundle into a complex shape and a solution thereto has been desired long.
The present invention has been accomplished in view of the above problems, and an object of the invention is to use fibers as an ink absorber and thus to provide an ink absorber suitably fit to a complex configuration of ink tank, an ink tank using the ink absorber, a process for producing the ink tank, and an ink jet cartridge integrally incorporating the ink tank and an ink jet recording head.
A specific means for achieving the above object is an ink absorber housed in a housing of an ink tank and being capable of retaining ink, the ink absorber having an outer surface equal to or corresponding to a configuration of an inner surface of the housing and comprising a fiber material obtained by compressing a fiber body and thermally molding at least a surface thereof. This can solve the above various problems in the cases using the foam for the ink absorber and can provide the ink absorber fit well to a complex configuration of ink tank, which has been the technical subject in the ink absorbers utilizing the conventional felt.
Another aspect of the invention is an ink tank comprising an ink absorber capable of retaining ink and a housing for housing the ink absorber and having an air-communicating portion, wherein the ink absorber has an outer surface equal to or corresponding to a configuration of an inner surface of the housing and comprises a fiber material obtained by compression and thermal molding of at least a surface. This can provide the ink tank of a complex shape effective to utilize the limited space in the ink jet recording apparatus.
Another aspect of the invention is a process for producing an ink tank having an ink absorber capable of retaining ink and a housing for housing the ink absorber, comprising a first molding step of molding a continuous fiber aggregate of a rod shape or a plate shape with elasticity, a step of cutting the fiber aggregate thus molded to form a fiber body, a second molding step of compressing and thermally molding the fiber body to shape an outer surface thereof corresponding to a configuration of the inside of the housing, thereby forming an ink absorber, and a step of inserting the ink absorber into the inside of the housing. By this, the ink tank of the complex shape as discussed previously can be produced easily and cheaply.
A further aspect of the invention is a fiber body being an aggregate of many short fibers, used as a raw material for an ink absorber of an ink tank used in the ink jet recording apparatus, which has elasticity and which is obtained by cutting a continuous short-fiber aggregate of a rod shape or a plate shape a surface layer of which is thermally bonded, whereby in fabrication of the ink absorber having the outer surface corresponding to the configuration of the inner surface of the housing of the ink tank in the above fabrication steps, an intermediate product with good operability in fabrication apparatus can be provided.